How do you solve this? cosθ-tanθcosθ=0

First, lets note that . This leads us with the following problem:



Lets add sin on both sides, and we get:



Now if we divide with sin on both sides we get:



Now we can remember how cot is defined, it is (cos/sin). So we have:



Now take the inverse of cot and we get:


In general we have , the reason we have to add pi times n, is because it is a function that has multiple answers, see the picture: